Spring-loaded seal assembly

ABSTRACT

A seal assembly is provided. The seal assembly includes a first outer shim and a second outer shim The second outer shim is operably coupled to the first outer shim and comprises at least one substantially impermeable portion that spans across a gap between at least two turbomachine components. The second outer shim further engages the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is either coupled to at least a portion of an outer surface of the first outer shim or comprises an integral portion of the first outer shim The resilient member engages the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application No. 13/560,357, entitled “Layered Seal For Turbomachinery,” filed on Jul. 27, 2012, the entire contents of which are hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT

This invention was made with Government support under contract number DE-FC26-05NT42643, awarded by the Department Of Energy. The Government has certain rights in the invention.

BACKGROUND

The invention relates generally to a seal assembly and, more particularly, to seal assemblies for reducing or substantially eliminating leakage in a turbomachine such as a heavy-duty gas turbine or an aero-derivative gas turbine.

A turbomachine has a gas path, which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine area, and a gas outlet (or exhaust nozzle). Leakage of high pressure cooling flows between adjacent stator components in the turbomachine such as shrouds, nozzles, and diaphragms into a low pressure hot gas path may lead to reduced efficiency and may require an increase in burn temperature, and thereby an increase in NO_(x). Turbine efficiency may thus be improved by reducing or eliminating leakage locations.

Preventing leakage between adjacent stator components with seals may be challenging due to the fact that the seals must be durable enough to withstand several thousand hours of operation and flexible enough to compensate for assembly misalignment, different engaging surfaces, vibration during operation, and unequal thermal expansion between adjacent stator components.

Thus, there is a need to provide a seal assembly to reduce or substantially eliminate leakages between adjacent stator components. It is further desirable that such seals are durable enough to withstand several thousand hours of operation and flexible enough to compensate for assembly misalignment, different engaging surfaces, vibration during operation, and unequal thermal expansion between adjacent stator components.

BRIEF DESCRIPTION

The inventors of the present application have identified that a through leakage occurs through a gap left under a central metallic shim that does not extend to the bottom of the seal and an end-face leakage occurs through a gap between the ends of the cloth seal and the ends of a mating slot or cavity defined between adjacent stator components in conventional cloth seal embodiments. The use of the combination of a biasing resilient member on the top of a seal assembly and an impermeable outer shim on the bottom of the seal assembly is expected to reduce leakages.

In accordance with one embodiment, a seal assembly is provided. The seal assembly includes a first outer shim and a second outer shim The second outer shim is operably coupled to the first outer shim and comprises at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components. The second outer shim is further configured to engage the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is either coupled to at least a portion of an outer surface of the first outer shim or comprises an integral portion of the first outer shim The resilient member is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components. The resilient member may include a spring that may be configured to push the seal assembly downwards so that the second outer shim maintains a desired contact with the bottom surfaces of the cavity.

In another embodiment a seal assembly is provided. The seal assembly includes an outer shim comprising at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components. The outer shim is further configured to engage the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.

In yet another embodiment a turbomachine is provided. The turbomachine includes at least two turbomachine components and a seal assembly disposed in a cavity defined between the at least two turbomachine components. The seal assembly includes a first outer shim and a second outer shim The second outer shim is operably coupled to the first outer shim and comprises at least one substantially impermeable portion configured to span across a gap between the at least two turbomachine components. The second outer shim is further configured to engage the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is either coupled to at least a portion of an outer surface of the first outer shim or comprises an integral portion of the first outer shim The resilient member is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.

DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a cross-section of a portion of a turbomachine including a first turbomachine component, a second turbomachine component, and a seal assembly comprising a resilient member and first and second outer shims in accordance with one embodiment.

FIG. 2 is a seal assembly in accordance with another embodiment wherein one or more inner layers are present between the first and second outer shims.

FIG. 3 is a seal assembly in accordance with another embodiment, wherein the resilient member and the first outer shim are integral.

FIG. 4 is a seal assembly illustrating perpendicular extensions of the first and second outer shims, in accordance with one embodiment.

FIG. 5 is a seal assembly illustrating angled extensions of the first and second outer shims, in accordance with one embodiment.

FIG. 6 is a seal assembly illustrating perpendicular and angled extensions of the first and second outer shims, in accordance with one embodiment.

FIG. 7 is a seal assembly including extensions of the first outer shim beyond a horizontal axis, in accordance with one embodiment.

FIG. 8 is a seal assembly including the extensions of the first outer shim to the horizontal axis, in accordance with one embodiment.

FIG. 9 is a seal assembly including a curved “shepherds hook” first outer shim, in accordance with one embodiment.

FIG. 10 is a seal assembly including the curved “shepherds hook” first outer shim, in accordance with another embodiment.

FIG. 11 is a seal assembly where the extensions of the first outer shim are joined to extensions of the second outer shim, in accordance with one embodiment.

FIG. 12 is a seal assembly in accordance with another embodiment which includes a single outer shim

DETAILED DESCRIPTION

Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms “first”, “second”, and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the terms “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The term “or” is meant to be inclusive and mean one, some, or all of the listed items. The use of terms such as “including,” “comprising,” or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “top,” “bottom,” “side,” “middle,” “outer” and “interior” as used herein are meant to reflect relative, as opposed to absolute positions.

Also, the term “substantial” or “substantially” as used herein is a qualifier term to indicate that the characteristic is present but some deviation is allowed. The amount of allowable deviation can vary depending on the particular context. For example, “substantially planar” indicates a surface or plane is close to being exactly planar, but small deviations are included, for example, either an overall or local deviation of two to five degrees. The term “substantially impermeable” indicates a material that is either completely impervious to movement of any material or composition, or combination of materials or compositions, or reduces leakage to an acceptable limit (for example, in one embodiment, the leakage rate is reduced to half of the leakage rate in existing seals). Also, the term “substantially seal” indicates that the seal is firmly contacted with a surface or plane such that the possibility of leakage is eliminated (that is, leakage is nil) or is reduced to an acceptable limit. Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular seal embodiment may similarly be applied to any other seal embodiment disclosed herein.

Various embodiments of the present invention describe seal assemblies that may be configured for, or used with, any number or type of turbomachine components requiring a seal to reduce or substantially eliminate leakage between the turbomachine components.

FIG. 1 is a cross-section of a portion of a turbomachine 100 including a first turbomachine component 102 and a second turbomachine component 104, in accordance with one embodiment. In some embodiments, the first and second turbomachine components 102 and 104 may be two adjacent stator components such as, but not limited to, shrouds, nozzles, or diaphragms. In some embodiments, as shown in FIG. 1, the first and second turbomachine components 102 and 104 may be spaced apart so as to define a gap or gas leakage path 106 therebetween. The gap 106 may allow flow, such as airflow, between the first and second components 102 and 104. In some configurations, the first and second components 102 and 104 may be positioned between a first airflow 108, such as cooling airflow, and a second airflow 110, such as hot combustion airflow. The term “airflow” as used herein refers to the movement of any material or composition, or combination of materials or compositions, translating through the gap 106 between the first and second components 102 and 104.

As shown in FIG. 1, in some embodiments, the first turbomachine component 102 has a first recess 112 comprising a top surface 114 and a bottom surface 116. Similarly, as shown in FIG. 1, the second turbomachine component 104 has a second recess 118 comprising a top surface 120 and a bottom surface 122. In various embodiments, the first and second recesses 112 and 118 may be substantially aligned with each other for receiving a seal assembly 124 to reduce or substantially eliminate leakage between the first and second turbomachine components 102 and 104. In order to provide the alignment, the bottom surfaces 116 and 122 of the first and second recesses 112 and 118, respectively, may lie on a common plane and the top surfaces 114 and 120 of the first and second recesses 112 and 118, respectively, may lie on another common plane to provide even surfaces at the bottom and top surfaces of the first and second recesses 112 and 118. However, the first and second recesses 112 and 118 may have any size, shape, or configuration capable of accepting a seal therein. The area between the first and second recesses 112 and 118 defines a slot or a cavity that extends from within the first turbomachine component 102, across the gap 106, and into the second turbomachine component 104. In some embodiments, the seal assembly 124 may be disposed between the first and second turbomachine components 102 and 104 such that the seal assembly 124 may contact bottom surfaces of the cavity, which may be same as the bottom surfaces 116 and 122 of the first and second recesses 112 and 118, respectively. As shown in FIG. 1, in some embodiments, the seal assembly 124 may span across the gap 106 and engage the first and second turbomachine components 102 and 104 to thereby seal the gap 106. Also, as shown in FIG. 1, in some embodiments, the seal assembly 124 may not completely cover the bottom surfaces 116 and 122 but is in contact with substantial portion of the bottom surfaces 116 and 122. In some other embodiments, the seal assembly 124 may completely cover the bottom surfaces 116 and 122.

In some embodiments (not shown), due to manufacturing and assembly limitations or variations, as well as thermal expansion, movement and the like during operation, the first and second recesses 112 and 118 may be skewed, twisted, angled, or otherwise misaligned. In such embodiments, the seal assembly used may be flexible enough to account for such misalignment. For example, above referenced U.S. patent application No. 13/560,357 describes flexible seals to account for such misalignments.

As illustrated in FIG. 1, in some embodiments, the seal assembly 124 may include a first outer shim 126 and a second outer shim 128. The second outer shim 128 may be operably coupled to the first outer shim 126. The first outer shim 126 may include a first end portion 130, a second end portion 132, and a substantially impermeable intermediate portion 134 connecting the first and second end portions 130 and 132. As shown in FIG. 1, the intermediate portion 134 may be substantially planar (hereinafter referred to as “planar portion 134”) at least along a width “W1” of the seal assembly 124, in accordance with various embodiments of the invention. The second outer shim 128 may include a first end portion 136, a second end portion 138, and a substantially impermeable and planar portion 140 (hereinafter referred to as “planar portion 140”) configured to couple the first and second end portions 136 and 138 and further configured to extend at least along the width “W1” of the seal assembly 124. Further, in some embodiments, the width “W1” of the seal assembly 124 may be less than a width “W2” of the cavity defined by the first and second recesses 112 and 118. In some embodiments, in addition to being impermeable to prevent the passage of airflow through the seal assembly 124, the first and second outer shims 126 and 128 may be resistant, or at least tolerant, to high temperatures being produced within the turbomachine 100. In an exemplary embodiment, the first and second outer shims 126 and 128 may include a metal such as a cobalt-based alloy, for example, but not limited to, Haynes® 188 or Haynes® 25 (L605). In one embodiment, the thickness of each of the first and second outer shims 126 and 128 may be about 10 mils to about 100 mils In another embodiment, the thickness of the first and second outer shims 126 and 128 may range between about 10 mils to about 30 mils.

As shown in FIG. 1, in some embodiments, the planar portion 140 may be configured to span across the gap 106 between the first and second turbomachine components 102 and 104 and further configured to engage the turbomachine components 102 and 104 to substantially seal the gap 106. The sealing of the gap 106 achieved by the second outer shim 128 may be more efficient than the existing cloth seals when the material used to manufacture the second outer shim 128 is substantially impermeable. The leakage rate is reduced due to the portion 140 being substantially impermeable and planar. The planar aspect facilitates the portion 140 to be completely or substantially engaged with the bottom surfaces 116 and 122 of the first and second recesses 112 and 118.

As shown in FIG. 1, the seal assembly 124 further includes a resilient member 142, such as for example, a spring. In some embodiments, the resilient member 142 may be configured to engage the seal assembly 124 to contact the bottom surfaces 116 and 122 of the first and second recesses 112 and 118, respectively. In an exemplary embodiment, when the pressure difference across the seal assembly 124 may not be sufficient by itself to engage the seal assembly 124 into contact with the bottom surfaces 116 and 122, the resilient member 142 may be configured to constantly push the seal assembly 124 downwards so that the second outer shim 128 maintains a desired contact with the bottom surfaces 116 and 122. In one embodiment, the desired contact indicates that a substantial portion of a bottom surface (not shown) of the planar portion 140 of the second outer shim 128 is in contact with the bottom surfaces 116 and 122 such that the seal assembly 124 may substantially seal the gap 106. In another embodiment, the desired contact indicates that the entire bottom surface of the planar portion 140 is in contact with the bottom surfaces 116 and 122. In some embodiments, constant pressure by the resilient member to push the substantially impermeable shim 128 to achieve the desired contact, and thus substantially seal the gap 106, may result in reducing or substantially eliminating through (shown in FIG. 1) and end-face leakages between the two adjacent stator components.

Referring still to FIG. 1, the resilient member 142 may include a substantially planar portion 143. The substantially planar portion 143 may be configured to extend at least along a portion of the width “W1” of the seal assembly 124, in accordance with some embodiments. The term “at least along a portion” as used herein refers to extension along a small part of, a major part of, entire, or beyond, for example, width “W1” of the seal assembly 124. As illustrated in FIG. 1, in some embodiments, the resilient member 142 may further include a first arm portion 144 including a first end 146 and a second end 148, and a second arm portion 150 including a first end 152 and a second end 154. The first end 146 of the first arm portion 144 and the first end 152 of the second arm portion 150 may be operably coupled to opposing ends 156 and 158, respectively, of the substantially planar portion 143 of the resilient member 142, in accordance with one embodiment. Also, as shown in FIG. 1, in some embodiments, the second end 148 of the first arm portion 144 may be operably coupled to a portion of the top surface 114 of first recess 112, and the second end 154 of the second arm portion 150 may be operably coupled to a portion of the top surface 120 of the second recess 118. As used herein, “operably coupled” refers to a second end (148 or 154) of an arm portion (144 or 150) of the resilient member 142 being configured to contact with a top surface (114 or 120) of a recess (112 or 118) during operation. The resilient member may have any shape, size, configuration, or composition without deviating from the scope of the invention. For example, commonly assigned U.S. Patent Publication No. 2009/0085305 discloses different shapes, sizes, configurations, or compositions of springs, and is herein incorporated by reference in its entirety. One such embodiment is illustrated in FIG. 2, where the resilient member may comprise a leaf spring such that the planar portion 143, the first arm portion 144 and the second arm portion 150 may be formed from an integral bent sheet.

Referring again to FIG. 1, in one embodiment, the resilient member 142 may be coupled to at least a portion of an outer surface 160 of the first outer shim 126. The term “at least a portion” as used herein refers to a small part of, a major part of, entire, or extension beyond, for example, the outer surface 160 of the first outer shim 126. In another embodiment, the resilient member 142 may be integrated with the first outer shim 126 such that the resilient member 142 may comprise an integral portion of the first outer shim 126.

In one exemplary embodiment, the resilient member 142 may include, but is not limited to, spring steel or other wear-resistant material capable of withstanding the environment of the turbomachine 100, which the seal assembly 124 may experience. In another exemplary embodiment, the resilient member 142 may include a high-temperature creep resistant material selected from, for example, an austenitic nickel-chromium alloy such as Inconel X-750™, a nickel based alloy such as Rene-41™, or the like. The material of the resilient member 142 may be selected such that it provides flexibility to the resilient member 142 to bend, stretch or compress (and thus may have high tensile strength) to various shapes and sizes. In some embodiments, the resilient member 142 may have a thickness of about 3 mils to about 50 mils.

In some embodiments, a thickness of the seal assembly 124 before being disposed in the cavity may be greater than a thickness “T” of the cavity defined by the first and second recesses 112 and 118. In such embodiments, the thickness of the seal assembly 124 may be reduced during installation in the cavity to a thickness, which may be equal to the thickness T of the cavity, so as to accommodate the seal assembly 124 within the cavity. In such embodiments, the seal assembly 124 may be compressed to fit within the cavity, and thereby may include portions or components configured for such compression. In some embodiments, the compression may be achieved due to flexibility of the resilient member 142, which may be bent, stretched or compressed to any shape or size. For example, U.S. Patent Publication No. 2009/0085305 and U.S. patent application No. 13/306,090 are directed to seals with such “compression fit” features. U.S. patent application No. 13/306,090 is herein incorporated by reference in its entirety.

The first outer shim 126 and the second outer shim 128 may be operably coupled to one another using any known fastening means. In one exemplary embodiment, a weld or a braze may be positioned in a medial portion 162 of the width “W1” of the seal assembly 124. In such embodiments, the weld or braze may be configured to extend along the thickness of the seal assembly 124. Alternatively, in some other embodiments, other types of known fastening means such as an adhesive or a fastener may be used. In embodiments wherein the resilient member 142 and the first outer shim 126 are discrete components, the first outer shim 126, the second outer shim 128, and the resilient member 142 may be similarly operably coupled by any known fastening means, such as, but not limited to, weld, braze, adhesive, or fastener, or any combination thereof. U.S. Patent Publication No. 2009/0085305 and U.S. patent application No. 13/560,357 describe the use of various fastening means to couple various components of a seal assembly.

In various embodiments, the shapes and configurations of the first outer shim, the second outer shim, or the resilient member may vary. Moreover, in some embodiments, the seal assembly may include additional layers. Examples of such variations are provided in FIGS. 2-12.

FIG. 2 is a seal assembly 200 including a first inner layer 202 and a second inner layer 204 disposed between the first and second outer shims 126 and 128. In an exemplary embodiment, the inner layers 202, 204 may include a wire mesh woven cloth, a flat ribbon mesh woven cloth, a honeycomb structure, a corrugated shim, or a compliant shim, or any combination thereof. In one embodiment where the inner layers 202 and 204 are shims, the shape, size and configuration of the shims 202 and 204 may or may not be the same as that of the first and second outer shims 126 and 128. Although the seal assembly 200 depicts the first and second inner layers 202 and 204, the seal assembly 200 may include any number or type of inner layers. The first and second inner layers 202 and 204 may be any material, shape, size and configuration. In some embodiments, the first and second inner layers 202 and 204 may be more porous or flexible as compared to other components (such as the first and second outer shims 126 and 128) of the seal assembly 200. U.S. patent application No. 13/560,357 describes various shapes, sizes and configurations of exemplary shims and inner layers.

The seal assembly 200 of FIG. 2 includes a leaf spring 206 with a different shape than the resilient member 142 of FIG. 1. In some embodiments, the leaf spring 206 may include the planar portion 143, the first arm portion 144 and the second arm portion 150 that may be formed from an integral bent sheet. Various embodiments described above for the seal assembly 124 may be equally applied to the seal assembly 200. In one embodiment, the leaf spring 206 in FIG. 2 may be replaced with the resilient member 142 of FIG. 1. The fastening means described above with reference to FIG. 1 may be used to couple the inner layers 202 and 204 to the rest of the seal assembly 200.

The shapes of the first outer shim 126 or the second outer shim 128 or both may vary. FIGS. 3-12 depict different exemplary shapes of the outer shim 126, 128.

As shown in FIGS. 4-10, in some embodiments, the first outer shim 126 may additionally include a first extension 302 and a second extension 304 that may be operably coupled to the opposing first and second end portions 130 and 132, respectively, of the first outer shim 126. In some embodiments, the first and second extensions 302 and 304 may be configured to extend at least along a first portion (not shown) of the thickness of the seal assembly. The thickness or height of the first portion along which the first and second extensions 302 and 304 extend may vary across different embodiments, as shown in FIGS. 4-10.

As shown in FIGS. 3-6 and FIG. 12, in some embodiments, the second outer shim 128 may additionally include a third extension 306 and a fourth extension 308 that may be operably coupled to the opposing end portions 136 and 138, respectively, of the second outer shim 128. In some embodiments, the third and fourth extensions 306 and 308 may be configured to extend at least along a second portion (not shown) of the thickness of the seal assembly. The thickness or height of the second portion along which the third and fourth extensions 306 and 308 extend may vary across different embodiments, as shown in FIGS. 3-6 and FIG. 12. As used herein for the extensions 302, 304, 306, and 308, “operably coupled” refers to the extensions being either curved or bent integral to the respective outer shim or shims 126, 128, or separate elements that are physically attached to the respective outer shim or shims 126, 128. Similar to the planar portions 134 and 140, in various embodiments of the invention, the extensions 302, 304, 306, and 308 may also be substantially impermeable.

Due to the addition of the extensions 302, 304, 306 and 308 in the first and second outer shims 126 and 128, increased stiffness may be provided to the overall structure of the seal assembly. Moreover, due to the extensions 302, 304, 306 and 308, any possibility of unwanted material at the edges of the planar portions 134 and 140, for example, because of sharp edges of the planar portions 134 and 140 is avoided.

Referring to FIG. 3, this figure illustrates that in some embodiments, the resilient member 142 in the seal assembly 300 is an integral portion of the first outer shim 126. Additionally, the seal assembly 300 includes the third and fourth extensions 306 and 308 oriented substantially perpendicular to the planar portion 140 of the second outer shim 128.

FIG. 12 is a seal assembly 1200 in accordance with another embodiment wherein no first outer shim 126 is present. In this embodiment, the resilient member 142 and the second outer shim 128 are either coupled or integrated. In such embodiments, the second outer shim 128 may be interchangeably referred to as outer shim 128. As shown in FIG. 12, in some embodiments, the resilient member 142 in the seal assembly 300 may be operably coupled indirectly to at least a portion (not shown) of an inner surface 1202 of the outer shim 128, that is, via the optional first and second inner layers 202 and 204, which may be disposed between the outer shim 128 and the resilient member 142. Alternatively, in some other embodiments (not shown) where the first and second inner layers 202 and 204 are not present, the resilient member 142 may be either directly coupled to at least the portion of the inner surface 1202 of the outer shim 128 or an integral portion of the outer shim 128. In an exemplary embodiment, the resilient member 142 may be coupled (directly or indirectly) to some or entire top surface 1204 (which may be, for example, equivalent to a planar part of the inner surface 1202) of the planar portion 140 of the outer shim 128. Irrespective of whether the coupling is direct or indirect, the coupling between different components may be achieved using any known fastening means as described above.

Various embodiments described above for the seal assemblies 100, 200, and 1200 may be equally applied to the seal assembly 300 and seal assemblies of FIGS. 4-11. In one exemplary embodiment, the shape and configuration of the outer shim 128 or the resilient member 142 or both shown in FIGS. 3 and 12 may be replaced with the type shown in the seal assembly 100, 200. In another exemplary embodiment, the shape and configuration of the outer shim 128 shown in FIGS. 3 and 12 may be replaced with the type shown in any of FIGS. 4-11.

Referring to FIG. 4, in some other embodiments, the resilient member 142 in the seal assembly 400 is shown as being discrete from the first outer shim 126. As shown in FIG. 4, in some embodiments, the seal assembly 400 may include the first and second extensions 302 and 304 oriented substantially perpendicular to the planar portion 134 (shown in FIG. 4) of the first outer shim 126, in addition to the third and fourth extensions 306 and 308 oriented substantially perpendicular to the planar portion 140 of the second outer shim 128. Gaps 402 and 404 are provided between adjacent pairs of the extensions 302, 306 and 304, 308 to allow for flexibility and tolerance changes during seal compression.

Referring to FIG. 5, in some embodiments, a seal assembly 500 is depicted where the first and second extensions 302 and 304 of the first outer shim 126, and the third and fourth extensions 306 and 308 of the second outer shim 128 may be angled from the planar portions of the first and second outer shims 126 and 128 instead of being oriented in a substantially perpendicular manner.

Referring to FIG. 6, in some other embodiments, a seal assembly 600 is depicted where the first and fourth extensions 302 and 308 may be angled from the planar portions 134 and 140, respectively, and the second and third extensions 304 and 306 may be oriented substantially perpendicular to the planar portions 134 and 140, respectively. As shown in FIG. 6, the first extension 302 may extend to a horizontal axis X-X′ defined along the width of the bottom surface 116 of the first recess 112 (see FIG. 1) such that a bottom surface 602 of the first extension 302 may lie on the same plane as defined by the bottom surface 116.

Alternatively, in another embodiment (not shown), instead of the fourth extension 308, the second extension 304 may be angled from the planar portion 134 such that a bottom surface of the second extension 304 may extend to the horizontal axis X-X′ such that the bottom surface of the second extension 304 may lie on the same plane as defined by the bottom surface 122 of the second recess 118.

Referring to FIG. 7, a seal assembly 700 is depicted where the first and second extensions 302 and 304 of the first outer shim 126 may extend slightly beyond the horizontal axis X-X′ defined along the width of the bottom surfaces 116 and 122 (not shown in FIG. 7) of the cavity such that a plane defined by the bottom surface 602 and a bottom surface 702 of the first and second extensions 302 and 304, respectively, may be slightly below a plane defined by the bottom surfaces 116 and 122. The extension slightly beyond the horizontal axis X-X′ may facilitate in providing additional resistance to any through leakage that may occur in embodiments where the extension is only to the horizontal axis X-X′, in accordance with various embodiments. A thickness “T1” of a portion of the first extension 302 and a thickness “T2” of a portion of the second extension 304 defined between the bottom surfaces 116 and 122 of the cavity and the bottom surfaces 602 and 702 of the first and second extensions 302 and 304, respectively, may be small. Small thicknesses T1 and T2 may allow the planar portion 140 of the second outer shim 128 to be still completely or substantially engaged with the bottom surfaces 116 and 122 of the cavity. In some embodiments, the thicknesses T1 and T2 may be different or same.

As illustrated in FIG. 8, in some embodiments, a seal assembly 800 is depicted where the first and second extensions 302 and 304 of the first outer shim 126 may extend to the horizontal axis X-X′, such that the bottom surfaces 602 and 702 of the second extensions 302 and 304, respectively, are on the same plane as the bottom surfaces 116 and 122 of the cavity (See FIG. 1).

Referring to FIG. 9, a seal assembly 900 is depicted where the shape of the first outer shim 126 is a curved “shepherds hook”, in accordance with one embodiment. As shown in FIG. 9, in some embodiments, the first and second extensions 302 and 304 of the first outer shim 126 may be curved portions that may extend beyond the horizontal axis X-X′ such that a plane defined by the bottom surfaces 602 and 702 of the first and second extensions 302 and 304, respectively, may be below the plane defined by the bottom surfaces 116 and 122 (not shown in FIG. 9) of the cavity. Similar to the seal assembly 700 depicted in FIG. 7, the thicknesses T1 and T2 may be small enough to allow the planar portion 140 of the second outer shim 128 to still completely or substantially engage with the bottom surfaces 116 and 122 of the cavity.

FIG. 10 depicts a seal assembly 1000 where the shape of the first outer shim 126 is the curved “shepherds hook”, in accordance with another embodiment. As shown in FIG. 10, in some embodiments, the first and second extensions 302 and 304 of the first outer shim 126 may be curved portions that may extend to the horizontal axis X-X′, such that the bottom surfaces 602 and 702 of the first and second extensions 302 and 304, respectively, are on the same plane as the bottom surfaces 116 and 122 (not shown in FIG. 10) of the cavity.

As described above, the extension of the first and second extensions 302 and 304 to or slightly beyond the bottom surfaces 116 and 122 of the cavity may be helpful to provide additional resistance to the through leakage. Irrespectively, in some embodiments, the end-face and through leakages may be eliminated or substantially reduced using the planar portion 140 of the second outer shim 128 without the first, second, third, and/or fourth extensions 302, 304, 306, 308.

Referring to FIG. 11, a seal assembly 1100 is depicted that is similar to the seal assembly 400 depicted in FIG. 4, except that the first and third extensions 302 and 306 are joined to close a gap 402 therebetween, and the second and fourth extensions 304 and 308 are joined to close another gap 404 therebetween. The seal assembly 1100 may result in a structure that is much stiffer than that provided when there are no extensions. Moreover, due to the closed enclosure, collection of unwanted material at the edges of the planar portions is avoided.

The seal assemblies disclosed in accordance with various embodiments of the invention may reduce the leakage between adjacent turbomachine components so as to improve overall system performance and efficiency. Various embodiments of the invention describe the use of the combination of a biasing resilient member (such as 142 or 206) on the top of a seal assembly (such as 124, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, or 1200) and an impermeable outer shim (such as the second outer shim 128) on the bottom of the seal assembly to reduce leakages. A planar portion (such as 140) of the impermeable outer shim may engage with bottom surfaces of a cavity that extends between a first turbomachine component (such as 102) and a second turbomachine component (such as 104) to eliminate or substantially reduce the through and end-face leakages. The impermeable outer shim on the bottom of the seal assembly may also result in reducing other types of leakages such as around leakage that may otherwise occur around the seal assembly. In some exemplary embodiments, the cooling airflow may enter in the area between the impermeable outer shims on top and bottom of the seal assembly; however, the cooling airflow will be blocked by the planar portion (such as 140) of the impermeable outer shim on the bottom from merging with the hot combustion airflow, thereby preventing around leakage.

Moreover, some extensions (302, 304, or any combination thereof) of the impermeable outer shim, for example, to or slightly beyond the bottom surfaces (such as 116 and 122) of the cavity may be helpful to provide additional resistance to the through leakage. Overall leakage rate through the seal assemblies of various embodiments of the invention may be reduced by, for example, thirty percent or more than that achieved using the existing cloth seals. Specifically, various embodiments of the invention may reduce or substantially eliminate end-face and through leakages between adjacent turbomachine components.

Seal assemblies as described in accordance with various embodiments are durable enough to withstand several thousand hours of operation and flexible enough to compensate for assembly misalignment, different engaging surfaces, vibration during operation, and unequal thermal expansion between adjacent stator components. In some embodiments, the resilient member or “spring” may be resilient enough to accommodate vibrations during operation.

While the dimensions and types of materials described herein define the parameters of various embodiments, they are by no means limiting and are merely exemplary. It is to be understood that a skilled artisan will recognize the interchangeability of various features from different embodiments and that the various features described, as well as other known equivalents for each feature, may be mixed and matched by one of ordinary skill in this art to construct additional systems and techniques in accordance with principles of this disclosure. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. 

What is claimed is:
 1. A seal assembly comprising: a first outer shim; a second outer shim operably coupled to the first outer shim, wherein the second outer shim comprises at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components and further configured to engage the at least two turbomachine components to substantially seal the gap, wherein the substantially impermeable portion is substantially planar at least along a width of the seal assembly; and a resilient member coupled to at least a portion of an outer surface of the first outer shim or comprising an integral portion of the first outer shim, wherein the resilient member is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
 2. The seal assembly of claim 1, wherein the resilient member comprises: a substantially planar portion configured to extend at least along the portion of the width of the seal assembly; a first arm portion including a first end and a second end; and a second arm portion including a first end and a second end, wherein the first end of the first arm portion and the first end of the second arm portion are operably coupled to opposing ends of the substantially planar portion of the resilient member.
 3. The seal assembly of claim 2, wherein the second end of the first arm portion and the second end of the second arm portion are operably coupled to top surfaces of the cavity defined between the at least two turbomachine components.
 4. The seal assembly of claim 1, further comprising at least one inner layer disposed between the first outer shim and the second outer shim.
 5. The seal assembly of claim 4, wherein the at least one inner layer comprises at least one of a wire mesh woven cloth, a flat ribbon mesh woven cloth, a honeycomb structure, a corrugated shim, or a compliant shim.
 6. The seal assembly of claim 1, further comprising a first extension and a second extension, operably coupled to opposing end portions of the first outer shim and configured to extend at least along a first portion of a thickness of the seal assembly.
 7. The seal assembly of claim 1, further comprising a third extension and a fourth extension, operably coupled to opposing end portions of the second outer shim and configured to extend at least along a second portion of a thickness of the seal assembly.
 8. The seal assembly of claim 1, wherein the second outer shim, the resilient member, and the first outer shim are operably coupled by one of a weld or a braze positioned in a medial portion of the width of the seal assembly, the weld or the braze configured to extend along a thickness of the seal assembly.
 9. The seal assembly of claim 1, further comprising an adhesive or a fastener for operably coupling the second outer shim, the resilient member, and the first outer shim.
 10. The seal assembly of claim 1, wherein the seal assembly is configured to be disposed in the cavity defined between the at least two turbomachine components, wherein the cavity includes a thickness less than a thickness of the seal assembly.
 11. The seal assembly of claim 1, wherein the resilient member includes a creep resistant nickel based alloy.
 12. The seal assembly of claim 1, wherein at least the first outer shim and the resilient member comprise an integral element.
 13. A turbomachine comprising: at least two turbomachine components; a seal assembly disposed in a cavity defined between the at least two turbomachine components, wherein the seal assembly comprises: a first outer shim; a second outer shim operably coupled to the first outer shim, wherein the second outer shim comprises at least one substantially impermeable portion configured to span across a gap between the at least two turbomachine components, and further configured to engage the at least two turbomachine components to substantially seal the gap, wherein the substantially impermeable portion is substantially planar at least along a width of the seal assembly; and a resilient member coupled to at least a portion of an outer surface of the first outer shim or comprising an integral portion of the first outer shim, wherein the resilient member is configured to engage the seal assembly to contact bottom surfaces of the cavity defined between the at least two turbomachine components.
 14. The turbomachine of claim 13, wherein the resilient member comprises: a substantially planar portion configured to extend at least along a portion of the width of the seal assembly; a first arm portion including a first end and a second end; and a second arm portion including a first end and a second end, wherein the first end of the first arm portion and the first end of the second arm portion are operably coupled to opposing ends of the substantially planar portion of the resilient member.
 15. The turbomachine of claim 14, wherein the second end of the first arm portion and the second end of the second arm portion are operably coupled to top surfaces of the cavity defined between the at least two turbomachine components.
 16. The turbomachine of claim 13, wherein the seal assembly further comprises at least one inner layer disposed between the first outer shim and the second outer shim.
 17. The turbomachine of claim 13, wherein the seal assembly further comprises a first extension and a second extension, operably coupled to opposing end portions of the first outer shim and configured to extend at least along a first portion of a thickness of the seal assembly.
 18. The turbomachine of claim 13, wherein the seal assembly further comprises a third extension and a fourth extension, operably coupled to opposing end portions of the second outer shim and configured to extend at least along a second portion of a thickness of the seal assembly.
 19. A seal assembly comprising: an outer shim comprising at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components and further configured to engage the at least two turbomachine components to substantially seal the gap, wherein the substantially impermeable portion is substantially planar at least along a width of the seal assembly; and a resilient member configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
 20. The seal assembly of claim 19, wherein the seal assembly further comprises at least one inner layer disposed between the outer shim and the resilient member. 